1. Technical Field
The present invention relates to an optical device, a light source device, and a projector.
2. Related Art
In the related art, a projector that modulates, in response to image information, light emitted from a light source and projects an image onto a projection surface such as a screen has been known. An optical element in the projector generates heat with the light from the light source, and therefore, a technique for cooling this optical element has been proposed (see, for example, JP-A-2014-123014 and JP-A-2012-13897).
JP-A-2014-123014 discloses a light source device including an excitation light source portion that emits excitation light and a fluorescence emitting portion. The fluorescence emitting portion includes a phosphor plate including a phosphor layer, a substrate on which the phosphor plate is placed, and a heat sink. The phosphor plate is irradiated with the excitation light emitted from the excitation light source portion and emits fluorescence in a wavelength band different from that of the excitation light. The heat sink includes a plurality of fins and dissipates the heat of the substrate (optical element) on which the phosphor plate is placed.
JP-A-2012-13897 discloses a light source device including a semiconductor laser, a dichroic mirror, a reflective color wheel, a rotation mechanism, and fins that function as a heat dissipating portion of the reflective color wheel. The fins are formed so as to be rotated by the rotation mechanism and diffuse the air with centrifugal force.
However, in the technique disclosed in JP-A-2014-123014, the fins of the heat sink extend long to the side opposite to the phosphor plate, causing a problem of increasing the size of the device.
Moreover, in the fins disclosed in JP-A-2012-13897, it is difficult to sufficiently use a flow of air generated by rotation, and it is conceivable that the number of revolutions of the fins will increase or that the size of the fin will increase. An increased number of revolutions of the fins leads to a problem of increasing noise due to wind noise, and an increased size of the fin leads to a problem of increasing the size or weight of the light source device.